Does it worth? If your game needs it, it worths. Is your game 2D or 3D? Are your models complex (high polygon count) or simple?

Calculating vertex positions on the CPU then updating the dynamic vertex buffer will work, and having CPU access to the transformed geometry may be useful if your geometry is not complex; you could do hit-testing on the geometry itself rather than an approximation. Notice here I'm talking about skinning, not animation. Animation is always done on the CPU. That said, the big boys usually skin their big meshes on the GPU.